Coating Device for Coating an Elongated Substrate

ABSTRACT

A device and system for dynamically applying liquid to a single thread for a thread consuming device as said thread moves relative to the device along a path of movement. The device is configured to apply liquid to said thread by means of an electrospraying unit. A method for applying liquid to a single thread for a thread consuming device as said thread moves relative to the device along a path of movement is also provided.

FIELD OF THE INVENTION

The present invention relates coating of a thread and, moreparticularly, coating in form of dyeing said thread with a liquid, suchas a liquid comprising ink.

BACKGROUND ART

Devices for embroidering a medium, such as cloth, in accordance with adesign generated using a personal computer are known. Such devices areadvantageous in that they make it easy to embroider a complex design.

However, the color of the embroidered design depends on the color of thethread. Therefore, when embroidering is carried out using differentcolored threads, the thread used in the apparatus must be changed eachtime a different color is to be embroidered. To change the thread, thethread currently in the apparatus must be cut and removed, and anotherthread having a different color must be threaded in the apparatus andpassed through the hole of an embroidery needle. This slows down theembroidery operation and makes it more costly.

Embroidery devices for industrial use and sewing machines capable ofembroidering are known. However, it is necessary to change an upperthread corresponding to the requested color, and it is necessary todesign the embroidery pattern taking into account the limitations of theembroidery machine and available threads, and then to embroider withthese available threads by exchanging the upper thread, as needed.Hence, a great deal of time and work is required to embroider indifferent colors using this technique. In addition, since many threadsof various colors must be used, the colors are limited to the number ofthreads used, and therefore it is cumbersome to embroider in a largenumber of colors. For example, when embroidering in colors varyingcontinuously from dark green to yellow, it is necessary to providethreads of numerous colors and change them in accordance with thedesired color, and therefore the ability of such embroidery techniquesto express color variations is limited.

In recent years, textile printing using ink jet printing techniques(Digital Textile Ink Jet Printing) has been put to practical use andfine printed material has been readily produced. However, it isimpossible with such techniques to provide the three-dimensional effectspossible with embroidery.

U.S. Pat. No. 6,189,989 B1 discloses a printing device aiming tomitigate at least some of the above mentioned problems by an ink jetprinting apparatus having a station for dyeing a thread for embroideringby discharging ink onto the thread from an ink jet head. According toone aspect, a printing controller controls the amount of ink dischargedper unit time onto the thread according to the speed of the relativemovement of the thread and the ink jet head. However, the device iscomplex and the ink jet head provides unsatisfactory ink coverage of thethread. It is desirable to obtain as small droplets as possible, toobtain an optimized result. Therefore, an ink jet head ink nozzle needsto be sufficiently small. Furthermore, a small nozzle is needed tomaintain ink inside ink jet head when no ink discharge is wanted.Further, the larger the nozzle diameter, the larger the dischargeddroplets become, which eventually lead to leakage of ink. A small inkjet nozzle is typically also accompanied by technical problems, such asincreased risk of clogging, leading to the risk of uneven inkdistribution, and short life span and/or costly. All in all, thisjeopardizes the precision of the ink distribution, which is vital for athread coloring thread consuming machine, since failure in this respectleads to wrong color appearing on the wrong position.

Hence, an improved coating device and thread consuming system solvingthe above described deficiencies would be beneficial.

SUMMARY

An object of the present invention is to provide a novel device forapplying liquid, such as ink, to a single thread as said thread movesrelative to the device along a path of movement, which device isimproved over prior-art devices of the type discussed above.

A particular object of the present invention is to provide a novelcoating device for dynamically applying liquid, such as ink, to a singlethread for a thread consuming device as said thread moves relative tothe coating device along a path of movement, which coating device isimproved over prior-art devices of the type discussed above.

A particular object of the present invention is to provide a novelcoating device for dynamically applying ink to a single thread for anembroidery machine as said thread moves relative to the coating devicealong a path of movement, which coating device is improved overprior-art coating devices of the type discussed above.

A particular object of the invention is to provide such an improvedcoating device, providing a better ink coverage of the thread.

Another object is to provide a less complex coating device.

Another object is to provide a coating device allowing for decreasedrisk of clogging and improved exactness of ink distribution.

Another object is to provide a coating device with increased life span.

These and other objects, which will appear from the followingdescription, have now been achieved by a device, a system and anembroidering method according to the appended independent claims.Advantageous embodiments are set forth in the dependent claims.

A coating device according to the invention handles application of inkto a thread and is typically fitted into a thread-consuming devicecomprising other machine elements, such as means for feeding the threadand means for embroidering using the thread.

A coating device according to a first aspect of the invention issuitable for dynamically applying ink to a single thread for embroideryas said thread moves relative to the coating device along a path ofmovement. The coating device is configured to apply ink to said threadby means of an electro spraying unit comprising at least one emitter,thread guiding means, ink supply means, voltage supplying means, counterelectrode means and an ink flow controller. The voltage supplying meansis arranged to supply a variable voltage or a modulated voltage, such asan alternating voltage. Each respective emitter is suitable fordischarging ink from a respective discharge edge, such as a dischargetip or a discharge orifice, towards the thread in a discharge direction,such that a respective discharge zone is formed. Further, the threadguiding means is configured to guide the thread through each respectivedischarge zone. The ink supply means is suitable for supplying ink tosaid at least one emitter, and the voltage supplying means is configuredto provide an electric potential between the at least one emitter andthe counter electrode means. Also, said emitter and said at least onecounter electrode means are configured such that an electric field iscreated between each respective emitter and the counter electrode meansto obtain the discharge zone of each respective emitter. Further, theink flow controller is configured to control the ink supply means andthe voltage supplying means in response to a control signal forcontrolling ink output.

Such a coating device provides improved ink coverage on said thread.

According to an embodiment of the invention, the coating devicecomprises a diversion electrode means configured to affect the path ofmovement of emitted ink by means of at least one electric field. Thediversion electrode may accomplish by-passing of undesired drops ofliquid from the flow path towards the thread. For example, the first setof droplets from the emitter may be of unknown or unwanted size orpotentially contaminated, and thus being undesired to hit the thread.The diversion electrode may also be used to direct droplets towards thethread, by alternating its potential in comparison with its settingduring by-passing mode. In this way mechanical alignment may be avoided.It is also possible to let the diversion electrode alternate inpotential or being applied with a potential sequentially to by-passdroplets passed the thread or to allow droplets to reach the thread. Thediversion electrode may also be positioned such that it may trap“escaping” droplets.

Such a coating device makes it possible to dynamically adjust thedirection of discharge of ink and/or the shape of the discharge zone.This in turn leads to lower requirements on mechanical tolerances of theguiding means and thus provides for a less expensive and lesscomplicated coating device.

According to a further embodiment, said coating device comprises aplurality of emitters arranged in a monolithic block. This provides forimproved precision of ink application to the thread.

According to another embodiment, a plurality of emitters is arranged inseries along the path of movement of the thread. This makes it possibleto use multiple emitters, thereby providing improved ink coverage. Also,it provides a simple and inexpensive arrangement that makes it possibleto hit the thread with ink from all around the thread in the case ofthreads that are twisting/rotating along their respective longitudinaldirection.

According to an embodiment, the one or more emitters are arrangedperpendicularly relative the path of movement of the thread. This bringsthe advantage that the degree of coverage is increased, since the inktypically hits the thread more symmetrically.

According to a further embodiment, shielding means are provided betweenthe emitters. The shielding means are configured to electrostaticallyshield the discharge zones from each other. This promotes independentoperation of adjacent emitters, since charged droplets from one emitter,or the emitters respective electrical field, will not affect theperformance of other emitters.

According to yet an embodiment, the shielding means is configured to beconnected to electric ground. This arrangement makes is possible tocontinuously remove excess charges from ink droplets hitting theshielding means.

According to another embodiment, each respective emitter is coated witha hydrophobic material. The hydrophobic coating prevents ink fromwetting over outer surfaces of the emitter, which in turn isadvantageous since fluid on the outer surface affects the droplet sizeand frequency of emission of droplets, and also the direction andstability of droplets thereby making it difficult to control inkdischarge.

According to an embodiment, the at least one emitter comprises acapillary tube with a central passage defining the discharge edge, whichin this embodiment comprises a tip with an orifice. The capillary tubeis commonly available as such, and used in a coating device according tothe invention it makes it possible to lower production costs whilemaintaining high precision. Further, the capillary tube consumes verylittle space and therefore provides for a compact design of said coatingdevice. Still further, the capillary tube allows for a capillary nozzlehaving low risk of clogging, due to its relatively large diameter, thusimproving life span and exactness of ink distribution.

According to a further embodiment, the at least one emitter comprises aplate with a thorough hole defining the discharge orifice. The plate iseasy to manufacture with high precision at low cost. Further, the platemakes it easy to connect the emitter to the voltage supplying means.Also, several emitters may be integrated into a monolithic constructionin an inexpensive manner by simply making the plate slightly bigger andproviding further holes.

According to yet an embodiment, each emitter is coupled to an individualink supply means comprised in said ink supply means. This brings theadvantage that the ink flow to each respective emitter can beindividually controlled, thus allowing for a more complex controlalgorithm to be used, which in turn makes it possible to simultaneouslycontrol the supply of a plurality of colors to the emitters of theelectro-spray unit and thereby provide a wide range of colors on thethread by appropriately dispensing various amounts of said plurality ofcolors.

According to an embodiment, an extractor electrode is provided adjacenteach respective discharge orifice. The extractor electrode promotesdischarge of ink from each respective emitter. Also, the voltagesupplying means is configured to provide a potential between eachrespective emitter and the extractor electrode. A device according tothis embodiment brings an advantage in that lower voltages may beutilized for promoting discharge of ink, since the distance between theextractor plate and the emitter is typically much smaller than thedistance between the emitter and the counter electrode means. Also,alignment between the nozzle and the thread is simplified by means ofthe E-field that the extractor electrode creates.

According to a further embodiment, the extractor electrode isplate-shaped and has a central through hole aligned with the dischargeorifice. This brings an advantage in that the plate is easy tomanufacture with high precision at low cost. Further, the plate makes iteasy to connect the extractor electrode to the voltage supplying means.Also, several extractor electrodes may be integrated into a monolithicconstruction in an inexpensive manner by simply making the plateslightly bigger and providing further holes.

According to yet an embodiment, the plate-shaped extractor electrode isarranged substantially perpendicular to the discharge direction. Thisbrings an advantage in that that it promotes a symmetric dischargepattern, which in turn increases the degree of coverage and provides fora more even ink covering of the thread.

According to yet another embodiment the plate-shaped extractor electrodecomprises a multitude of layers, such as two or three layers, saidlayers being arranged transversally to the through hole. The differentlayers may have different polarity, such that the polarity of the layercomprising the side facing the substrate, i.e. the thread, for examplemay be of a positive potential while the layer comprising the sidefacing the emitter is of a negative potential, when the emitter ispositively charged. In this embodiment the liquid being discharged fromthe emitter, and thus having the same potential as the emitter, may bekept from being attracted to the extractor electrode, and will continuetowards the substrate, i.e. the thread.

According to an embodiment, the electrospraying unit is provided with athread contacting means configured to provide electrical contact betweenthe voltage supplying means and the thread. The voltage supplying meansis also configured to provide a potential between each respectiveemitter and the thread. This brings an advantage in that it is possibleto adjust the potential between the emitter and the thread. This in turnmakes it possible to remove electrical charges that ink droplets bringto the thread. Further it makes it possible to at least partly use thethread as an electrode of the counter electrode means. Also, it makes itpossible to better attract satellite ink droplets to the thread, thusreducing ink consumption, increasing ink coverage on the thread andreducing contamination of surrounding machine elements.

According to another embodiment, the counter electrode is the thread.This brings a further advantage in that no other electrode is needed forthe counter electrode means.

According to yet an embodiment, the thread contacting means isconfigured to contact the thread at a position in which the thread hasalready passed a discharge zone. This brings an advantage in thatelectrical charges brought by droplets of ink in the discharge zone willbe removed before they distract the droplets from other nozzles alongthe path of movement of the thread.

According to an embodiment, the thread contacting means is configured tocontact the thread before it passes the first discharge zone along thepath of movement. This brings an advantage in that any electricalcharges present on the thread will be removed before it reaches thefirst discharge zone along its path of movement. This in turn providesfor better control of the threads ability to receive ink droplets.

According to a further embodiment, the coating device is provided with awetting means configured to make the thread more electrically conductiveby application of a wetting agent, such as an electrically conductiveliquid. This brings an advantage in that a wider selection of materialscan be used for said thread despite any need of having a conductivethread. Further it typically makes the thread more prone to absorbingink droplets applied thereto. The wetting of the thread may also improvecolor mixing and soaking of the thread. When the wetting of the threadis performed to improve color mixing and soaking of the thread, thewetting agent is selected such that its characteristics are similar tothe liquid characteristics of the liquid, such as an ink, intended tocoat the thread. If the liquid, such as an ink, is a water-based ink, apolar wetting agent, such as a protic or aprotic polar wetting agent,may be selected, such as water; ethanol; methanol; acetic acid;propanol; butanol; formic acid; ethyl acetate; acetone; acetonitrile;etc., and if the liquid, such as an ink, is non polar, such as oilbased, a non-polar wetting agent may be selected, such as alkanes, inform of pentane, cyclopentane, hexane, etc.; benzene; toluene;chloroform; diethyl ether; etc. Of course, combinations of thesespecific wetting agents are also within the ambit of the invention, aslong as the wetting agent aims at having the same characteristics as theliquid intended to coat and/or soak the thread.

According to yet an embodiment, the ink-flow controller is configured tooperate in a micro dripping mode. By operating the ink-flow controllerin the micro dripping mode, a flow of ink dispersed in droplets may beachieved, which in turn provides for a good ink coverage on the thread.

According to a further embodiment of the invention, the coating devicefurther comprises a fixation device for fixing non-fixated ink to thethread. Thereby, contamination of the system by non-fixated ink isprevented. Also, smearing of non-fixated ink along the thread isprevented.

According to an embodiment, the fixation device is configured to fix theink to the thread before non-fixated ink reaches the guiding means afterthe discharge zone. Thereby, non-fixated ink is prevented from beingscraped off the thread when the thread passes a thread guiding means.

According to yet an embodiment, the coating device further comprises atleast one treatment device for treatment of the thread before coloring,after coloring, after fixating, or a combination thereof. Thereby,sewability of the thread may be improved before the thread reaches thethread consuming device. The treatment device may be used singly,separately, or in combination with a coating device and/or threadconsuming device, such as a coating device and/or thread consumingdevice, wherein the thread is coated by means of electro spaying, inkjet, or similar coloring techniques.

According to an embodiment, the treatment device is configured toreceive the thread after the fixating device. Thereby, the fixatingdevice is prevented from negatively affecting sewability of the threadafter the thread has passed the treatment device.

According to an embodiment, the treatment device is configured toreceive the thread before the electrospraying unit. Thereby, the threadmay be pretreated to enhance coloring ability, enhancing sewability,etc., before the thread enters the electrospraying unit.

According to a further embodiment, the treatment device is configured towash the thread. Washing of the thread effectively improves sewabilityof the thread and removes any dust or other unwanted substances presenton the thread. Washing may be performed before and/or after the fixatingunit, and after coloring.

According to yet an embodiment, the treatment device is configured tolubricate the thread. Thereby, lubricity of the thread is increased,wherein sewability is typically also improved. Lubricating may beperformed before and/or after the fixating unit, and after coloring.

According to another aspect of the invention an embroidery system isprovided. The system comprises a coating device according to anembodiment of the invention. Further, the system comprises threadfeeding means, embroidery means and a pattern controller. The threadfeeding means is configured to feed the thread through the guiding meansof the coating device. The embroidery means is suitable for embroideringa pattern on an object using the thread based on pattern information.Also, the pattern controller provides control signals to said ink flowcontroller in response to at least the pattern information. Such asystem brings an advantage in that embroidery may be performed withimproved ink coverage and a higher degree of ink coverage of the threadembroidered.

According to yet an aspect of the invention a method of applying ink toan embroidery thread by means of a coating device according to anembodiment of the invention is provided. The method comprises a step offeeding the thread through the coating device while discharging ink ontosaid thread using said electrospraying unit. This method brings anadvantage in that it provides improved ink coverage and a higher degreeof ink coverage of the thread embroidered.

According to another embodiment of the invention, the method furthercomprises a step of wetting the thread before feeding said portionthrough a discharge zone. Wetting the thread makes it more electricallyconductive and typically also improves its ability to quickly absorb inkdroplets. Wetting also improves color mixing.

The method may further comprise controlling the wetting with regards tothe amount of the wetting agent used in relation to the threadconsumption to achieve a certain color quality (uniformity), betterfixation and/or better sewability.

The method may also comprise controlling the lubrication with regards tothe amount of the lubricant used in relation to the thread consumptionto achieve a certain color quality (uniformity), better fixation and/orbetter sewability.

BRIEF DESCRIPTION OF THE DRAWINGS

Each one figure of FIGS. 1-6 shows a schematic view of a coating deviceaccording a respective embodiment of the invention.

FIG. 7 shows a schematic view of an embroidery system according to anembodiment of the invention.

DETAILED DESCRIPTION

As previously mentioned, an aspect of the invention relates to a devicefor dynamically applying liquid, such as ink, to a single thread as saidthread moves relative to the device along a path of movement. In thisway, a thread may be coated or soaked with a liquid, such as an ink. Thedevice is configured to apply liquid to the thread by means of anelectrospraying unit. More specifically, the device is a threadconsuming device, such as an embroidery machine, for applying ink to asingle thread, such that the thread may be coated with said liquid, suchas ink. When the device is a thread consuming device, such as anembroidery machine, for applying ink to a single thread, the device maybe said to be a coating device. A thread may be glass fiber thread; athread of wool; a thread of cotton; a synthetic thread; a metallicthread; a thread being a mixture of wool, cotton, polymer, or metal; ayarn; filament; or any elongated substrate that is intended and/or beingsuitable for being applied with liquid, such as ink.

A coating device 100 according to a first embodiment of the inventionwill now be described with reference to FIG. 1. The coating device 100comprises an electrospraying unit comprising an emitter 101. The coatingdevice 100 also comprises a thread guiding means 102, ink supply means103, voltage supply means 104, counter electrode means 105 and an inkflow controller 106. The emitter 101 is suitable for discharging inkthrough the use of a discharge unit, such as an emitter edge 107, suchas an emitter tip or orifice, towards the thread T in a dischargedirection such that a respective discharge zone 108 is formed. Byapplying an electrical field over a surface comprising one or moreedges, on which ink is applied, an electrical field which is stronger atthe edge(s) is generated which causes the ink (being a liquid) todisperse. In one embodiment the emitter edge is a tip arranged with anorifice through which ink can be supplied to the emitter tip.

In one embodiment the emitter 101 is arranged for discharging inkthrough an orifice in the emitter tip 107 towards the thread T in thedischarge direction to form the discharge zone 108.

Further, the thread guiding means 102 is configured to guide the threadT through the discharge zone 108. The ink supply means 103 is suitablefor supplying ink to the emitter 101, and the voltage supplying means104 is configured to provide an electric potential between the emitter101 and the counter electrode means 105. Also, said emitter 101 and saidcounter electrode means 105 are configured such that an electric fieldcreated between the emitter 101 and the counter electrode means 105spans through the discharge zone 108. Further, the ink-flow controller106 is configured to control the ink supply means 103 and the voltagesupply means 104 in response to a control signal. The ink-flowcontroller 106 is preferably controlled such that a stable frequency ofdroplet discharge is achieved from the emitter 101, by appropriatelyadjusting the voltage controlling the potential between the emitter 101and the counter electrode means 105, while at the same timeappropriately controlling ink flow from the ink supply means 103 to theemitter 101 in relation to the desired color and relative speed of thethread. The droplet discharge may also be pulsed. This kind ofadjustment related to electrospraying is known in the art and variousknown types of spray characters, or ‘spraying modes’, may be achieved,such as ‘dripping’, ‘micro dripping’, ‘spindle’, ‘multispindle’,‘ramified-meniscus’, ‘oscillating-jet’, ‘precision’, ‘cone-jet’,‘multijet’, and ‘ramified-jet’. In a preferred embodiment of theinvention, the ink-flow controller 106 is configured to operate in the‘micro dripping’ spray mode, since that promotes intended ink coverageon the thread T. By operating the ink-flow controller 106 in the microdripping mode, a flow of ink dispersed in very small droplets may beachieved. The small size droplets are advantageous, especially for lowflows, and promote said intended ink coverage on the thread.

In the first embodiment, the counter electrode means 105 comprises asingle electrode. In another embodiment it could however compriseseveral electrodes.

Also, in the first embodiment the emitter 101 is a capillary pipe. Inanother embodiment it could however take other forms, such as a platewith a thorough hole defining the capillary. In a further embodiment,the hole is surrounded by a ridge extending from the plate in the axialdirection of the hole. The ridge prevents ink from spreading on theplate surface around the capillary.

Further, in the first embodiment the ink supply means 103 comprises asingle ink supply means connected to the emitter. In another embodiment,the ink supply means 103 may however comprise a separate ink supplymeans for each emitter or at least a separate ink supply means for agroup of emitters to be fed with same color ink.

In an embodiment (not shown), the guiding means 102 is configured totwist or rotate the thread along its length.

The guiding means 102 may be used singly, separately, or in combinationwith a coating device and/or thread consuming device, such as a coatingdevice and/or thread consuming device, wherein the thread is coated bymeans of electrospaying, ink jet, or similar coloring techniques. Thus,it is not necessarily so that only threads for dying withelectrospraying may benefit from the guiding means 102, but also othercoating devices using thread may benefit from it. As such, the guidingmeans 102 may solve problems independent of type of coating devices 100with electrospraying units.

A coating device 200 according to a second embodiment will now bedescribed with reference to FIG. 2. This coating device 200 is basicallyidentical to the one of the first embodiment except for some minorchanges. For example, it additionally comprises an extractor electrode109 in the form of an extractor plate. The extractor electrode 109comprises a through hole. The extractor electrode 109 is providedadjacent the discharge orifice 107, such that discharge of ink from theemitter may pass through the through hole, for promoting discharge ofink at a lower voltage. For this to work, the voltage supply means 104is modified such that it now also provides a potential between theemitter 101 and the extractor electrode 109. If the voltage supply meansalso is connected to the counter electrode means 105, said counterelectrode means 105 will further act as an ink collector, for minimizingink contamination of the rest of the equipment.

In one embodiment the extractor electrode 109 may comprise a multitudeof layers, such as two or three layers, said layers being arrangedtransversally to the extension of the through hole. Two layers ofelectrically conductive material may then be provided with differentpolarity, such that the polarity of the layer comprising the side facingthe substrate, i.e. the thread, for example may be of a positivepotential while the layer comprising the side facing the emitter is of anegative potential, when the emitter is positively charged. In this way,the liquid being discharged from the emitter, and thus having the samepotential as the emitter, may be kept from being attracted to theextractor electrode, and will continue towards the substrate, i.e. thethread. Between the two layers of conductive material comprising thesides facing the emitter and the thread, respectively, a layer of aninsulating material may be provided, to prevent short-circuiting. It isalso possible to have an air gap between the two layers.

A coating device 300 according to a third embodiment will now bedescribed with reference to FIG. 3. This coating device 300 is basicallyidentical to the one of the first embodiment 100 but additionallycomprises a thread contacting means 110. The thread contacting means 110is configured to provide electrical contact between the voltage supplymeans 104 and the thread T. For this to work, the voltage supply means104 is configured to provide a potential between the emitter 101 and thethread T, i.e. by means of an extra cable and an extra voltageregulator. Thus, a first potential is setup between the emitter 101 andthe extractor plate 109, while a second potential is setup between theemitter 101 and the thread T. This brings an advantage in that it ispossible to adjust the potential between the emitter 101 and the threadT. This in turn makes it possible to remove electrical charges that inkdroplets bring to the thread T, which would otherwise risk misleadingthe ink droplets. Further it makes it possible to at least partly usethe thread T as an electrode of the counter electrode means 105. Also,it makes it possible to better attract satellite ink droplets to thethread T, thus reducing ink consumption, reducing contamination of thedevice and increasing the dying quality.

A coating device 400 according to a fourth embodiment will now bedescribed with reference to FIG. 4. The coating device 400 is basicallyidentical to the coating device 300 of the third embodiment, except forthat it does not have a counter electrode 105 or an extractor electrode109. Further, the thread T is used as a counter electrode and no othercounter electrode exists. In order to achieve this, the threadcontacting means 110 is still used according to the same principle as inthe third embodiment, for providing an electric potential between theemitter 101 and the thread T. In order for the thread T to function asan electrode, at least a portion of the thread T has to be, or be made,electrically conductive such that electric connection exist between thethread contacting means 110 and a portion of the thread present in thedischarge zone 108. For example, the thread T may be continuously wetbefore being fed into the electrospraying unit.

The pretreatment of the thread as disclosed above, may also be achievedby heating, ionizing, corona or plasma treating the thread in order toimprove the colored thread's resulting characteristics as regardscoloring, structure, texture, sewabaility and friction to name a fewcharacteristics.

The thread contacting means 110 may also be used to charge the thread Teven if the thread is not electrically conductive. The charges of thethread then attract ink droplets as the charges pass the discharge zone.

A coating device 500 according to a fifth embodiment will now bedescribed with reference to FIG. 5. Here, the coating device 500 isbasically identical to the coating device 300 of the third embodiment,except for that the thread T is used as a counter electrode and no othercounter electrode exists. In order to achieve this, the threadcontacting means 110 is still used according to the same principle as inthe third embodiment, for providing a potential between the emitter 101and the thread T. As described above, with reference to the fourthembodiment, the thread T has to be made electrically conductive.

Furthermore, a coating device 600 according a sixth embodiment will nowbe described with reference to FIG. 6. Here, the coating device 600 issimilar to the coating device of the second, third and fifth embodiment,except for that it does not have any counter electrode means 105 andalso no thread contacting means 110. Thus, the only electric potentialused to discharge ink from the emitter 101 is provided by means of anextractor electrode 109, for example any one of the previously describedextractor electrodes.

In other embodiments, a plurality of emitters 101 could be provided inthe electrospraying unit. The emitters could either be used to dispensedifferent colors or to dispense the same color more than once.

According to further aspect of the invention an embroidery system 700 isprovided. Such a system will now be described with reference to FIG. 7.The system 700 according to this embodiment comprises a coating device100 according to the first embodiment of the invention, but couldhowever comprise a coating device according to any other embodiment ofthe invention. In addition to the coating device, the system 700comprises thread feeding means 111, embroidery means 112 and a patterncontroller (not shown). The thread feeding means 111 is configured tofeed the thread T through the guiding means 102 of the coating device100. The embroidery means 112 is suitable for embroidering a pattern ona substrate S using the thread T based on pattern information. Also, thepattern controller provides control signals to said ink flow controller106 in response to at least the pattern information, but possibly alsoother information, such as thread speed, ink type, thread type,temperature and humidity level in surrounding air. The patterninformation describes the pattern, i.e. what color is supposed to gowhere on the thread. The pattern information may also compriseinformation regarding the stitches and the path of the needle over thesubstrate S.

At one side of the coating device there is provided a thread supplier113, such as a thread bobbin or reel of thread, holding the thread T tobe fed into the coating device 100. Similar bobbins are known in theart.

After leaving the thread supplier 113 the thread T passes a threadtensioning device 114 configured to keep the thread T appropriatelytensioned during operation of the system 700. Similar thread tensioningdevices are known in the art.

After the coating device 100, the thread T passes an ink fixation device116, a buffer device 117 and a thread feeding means 111 configured tofeed or pull the thread T through said coating device 100 via saidguiding means 102. The feeding means 111 is driven by a suitableelectric motor 115 preferably controlled by the thread consumption ofthe thread consuming device. The buffer device 117 compensates for theintermittent thread speed of the embroidery means 112 and such bufferdevices 117 are known in the art. The ink fixation device 116 isconfigured to fixate the ink to the thread T before non-fixated inkreaches the guiding means 102 after the discharge zone. Thereby,contamination of the system 700 by non-fixated ink is prevented. Also,smearing of non-fixated ink along the thread T is prevented. In oneembodiment the ink fixation device 116 is a combined ink fixation anddrying device 116 for both drying the thread (T) and for fixating theink on the thread (T), for further prevention of contaminating thesystem 700.

Optionally, a thread treatment device 118 may be provided after thefixating device 116 treatment of the thread T in order to make thethread suitable for further handling of the thread consuming device (theembroidery means 112). The thread treatment device 118 is configured toreceive the thread T after the fixating device 116. Thread treatmentpost application of ink may for example comprise washing of the thread Tand/or lubrication of the thread T. The treatment device 118 may be usedsingly, separately, or in combination with a coating device and/orthread consuming device, such as a coating device and/or threadconsuming device, wherein the thread is coated by means ofelectrospaying, ink jet, or similar coloring techniques. Thus, it is notnecessarily so that only threads for dying with electrospraying maybenefit from the treatment device 118, but also other coating devicesusing thread may benefit from it. As such, the treatment device maysolve problems independent of coating devices 100 with electrosprayingunits.

When the thread T is colored by the coating device, the thread T maybecome stiffer and somewhat rougher. In order for the thread to besuitable for e.g. a thread consuming device performing sewing orembroidering, its ‘sewability’ should be good. Sewability is typicallyimproved by treatment with the thread treatment device. Typically,sewability is improved by improving the lubricity of the thread T, whichin turn is achieved by lubrication. The lubrication may be obtained bymeans of a wax- or silicone based lubricant.

Such a system 700 brings an advantage in that embroidery may beperformed with more even ink coverage and a higher degree of inkcoverage of the thread used for embroidering.

In one embodiment of the systems described above a maintenance unit (notshown) is arranged to clean and maintain the emitters, the wetting unit,the lubrication unit, thread treating unit, and/or washing unit. Themaintenance unit may comprise a cleaning means, such as a scraper, abrush, a pneumatic unit, and/or a hydrodynamic unit, for cleaning theemitter, the wetting unit, the lubrication unit, thread treating unit,and/or washing unit, through blowing or suction, or a flushing unit forflushing the emitter, the wetting unit, the lubrication unit, the threadtreating unit, and/or the washing unit.

The maintenance unit may further comprise an ink collector means forcollecting ink. The ink collector means may comprise a funnel, a sponge,a filter or a fan to name a few.

The maintenance unit may further comprise a fume directing means fordirecting ink fumes. The collector means may comprise or work accordingto a filter, a fan, a chimney effect possibly caused by the heatgenerated by the fixation device. The collector means may also bearranged to be controlled with electrical fields for capturing orcollecting fumes and other residue in specially adapted collectorvessels or filters.

The maintenance unit may further comprise a collector means forcollecting surplus lubrication, surplus washing solutions from thethread treating unit.

In one embodiment of the systems disclosed above the system may comprisemeans for controlling the wetting with regards to the amount of thewetting agent used in relation to unit of length of the thread toachieve a certain color quality (uniformity), better fixation and/orbetter sewability.

In one embodiment of the systems disclosed above the system may comprisemeans controlling the lubrication with regards to the amount of thelubricant used in relation to the thread consumption to achieve acertain color quality (uniformity), better fixation and/or bettersewability.

The systems above may be provided with a drop diversion unit, such as adiversion electrode (not shown). The diversion electrode may be providedwith the opposite potential of the emitter (and thus the liquid). Thediversion electrode may be positioned beneath the thread, i.e. on theopposite side of the thread in comparison with the emitter. When adiversion electrode is positioned on the opposite side of the thread incomparison with the emitter, the diversion electrode and/or the emittermay also be positioned laterally of the thread, such that the thread notis positioned in the direction of the emitter. In this way, thediversion electrode may direct the droplets towards the thread when thediversion electrode is provided with a different/opposite potential thanthe emitter, while droplets will miss the thread when no potential isapplied on the diversion electrode.

The diversion electrode may also be a separate diversion electrode unit,comprising a potential plate on each side of the droplet patch towardsthe thread. By applying a potential between the two plates the dropletmay be guided by the electrical field between the potential plates ofthe diversion electrode, towards or away from the thread. If the emitteris positioned laterally of the thread, the electrical field between thepotential plates of the diversion electrode may guide the dropletstowards the thread, and when the thread is positioned in the directionof the emitter, the electrical field between the potential plates of thediversion electrode may guide the droplets away from the thread.

As used herein, “embroidery” refers to forming patterns by stitching ona suitable base material or substrate.

Typically, each respective emitter is configured to discharge eithercyan, magenta, yellow or black ink, respectively, although other colorsand types of ink or liquids may be used, if desired. For example,instead of discharging colored ink, liquids for achieving specialeffects may be used, such as metallic-, neon- and/or special coating forsmart textiles, etc. Ink is discharged from the emitters in accordancewith the wanted color and at least the speed of the thread. That is,when the speed of the thread is low, ink is discharged at a low flowrate, and when the speed of the thread is high, ink is discharged at ahigh flow rate, whereby a thread dyeing operation can be performed infull cooperation with the embroidery apparatus.

In addition, plural inks of different colors can be mixed on a thread inaccordance with the pattern information so that the thread can be coatedin a substantially unlimited number of colors.

The invention also relates to methods of operating the coating devicesand systems according to the various embodiments described above.

The invention can be implemented in any suitable form includinghardware, software, firmware or any combination of these. The elementsand components of an embodiment of the invention may be physically,functionally and logically implemented in any suitable way. Indeed, thefunctionality may be implemented in a single unit, in a plurality ofunits or as part of other functional units. As such, the invention maybe implemented in a single unit, or may be physically and functionallydistributed between different units and processors.

Although the present invention has been described above with referenceto specific embodiments, it is not intended to be limited to thespecific form set forth herein. Rather, the invention is limited only bythe accompanying claims.

In the claims, the term “comprises/comprising” does not exclude thepresence of other elements or steps. Furthermore, although individuallylisted, a plurality of means, elements or method steps may beimplemented by e.g. a single unit or processor. Additionally, althoughindividual features may be included in different claims, these maypossibly advantageously be combined, and the inclusion in differentclaims does not imply that a combination of features is not feasibleand/or advantageous. In addition, singular references do not exclude aplurality. The terms “a”, “an”, “first”, “second” etc. do not preclude aplurality. Reference signs in the claims are provided merely as aclarifying example and shall not be construed as limiting the scope ofthe claims in any way.

1.-42. (canceled)
 43. A device for applying liquid to a single thread assaid thread moves relative to the device along a path of movement,wherein said device is configured to apply liquid to said thread bymeans of an electrospraying unit comprising: at least one emitter fordischarging liquid through a respective discharge nozzle towards thethread in a discharge direction, such that a respective discharge zoneis formed, thread guiding means configured to guide the thread througheach respective discharge zone, liquid supplier for supplying liquid tosaid at least one emitter, and voltage supply means, configured toprovide an electric potential between the at least one emitter and acounter electrode means, said emitter and said counter electrode meansbeing configured, such that an electric field created between eachrespective emitter and the counter electrode means discharges liquidinto said discharge zone.
 44. The device according to claim 43, whereinsaid electrospraying unit further comprises a liquid flow controllerconfigured to control the liquid supply means and the voltage supplyingmeans in response to a control signal.
 45. The device according to claim43, wherein said device comprises a plurality of said emitters.
 46. Thedevice according to claim 45, wherein the emitters are arranged inseries along said path of movement.
 47. The device according to claim43, wherein each respective emitter is coated with a hydrophobicmaterial.
 48. The device according to claim 43, wherein the at least oneemitter comprises a capillary tube with a central passage defining thedischarge orifice.
 49. The device according to claim 43, wherein eachemitter is coupled to an individual liquid supply means comprised insaid liquid supply means.
 50. The device according to claim 43, whereinsaid electrospraying unit is further provided with a thread contactingmeans configured to provide electrical contact between the voltagesupplying means and the thread, wherein the voltage supplying means isalso configured to provide a potential between each respective emitterand the thread.
 51. The device according to claim 43, further comprisinga treatment device in form of a wetting means, configured to make atleast a portion of the thread electrically conductive by application ofelectrically conductive liquid.
 52. The device according to claim 43,wherein the liquid-flow controller is configured to operate in a microdripping mode.
 53. The device according to claim 43, further comprisinga fixation device for fixing non-fixated liquid to the thread.
 54. Thedevice according to claim 43, further comprising a thread treatmentdevice for treatment of the thread.
 55. The device according to claim54, wherein the thread treatment device is configured to wash thethread.
 56. The device according to claim 54, wherein the threadtreatment device is configured to lubricate the thread.
 57. The deviceaccording to claim 43, wherein said device is a coating device forapplying ink on a single thread.
 58. The device according to claim 43,wherein the device is or is a part of a thread consuming device, fordynamically applying liquid, such as ink, to a single thread.
 59. Thedevice according to claim 58, wherein the thread consuming device is asewing machine or an embroidery machine, for dynamically applyingliquid, such as ink, to a single thread.
 60. A system for applyingliquid, such as ink, to a single thread, said system comprising: adevice according to claim 43; and thread feeding means configured tofeed the thread through said thread guiding means.
 61. The systemaccording to claim 60, wherein said system is an embroidery systemfurther comprising: embroidery means, for embroidering a pattern on asubstrate using the thread, based on pattern information, and a patterncontroller providing control signals to a liquid flow controller inresponse to at least the pattern information.
 62. A method of applyingliquid, such as ink, to a thread, comprising the steps: feeding a threadthrough a discharge zone; applying a voltage between at least oneemitter and a counter electrode means, and electrospraying liquid atsaid thread as a result of said voltage.
 63. The method according toclaim 62, further comprising applying liquid, such as ink, to the threadby means of a device according to claim 43, and feeding a thread throughthe device according to claim 43 while discharging liquid onto saidthread using said electrospraying unit.
 64. The method according toclaim 62, comprising a further step of wetting at least a portion of thethread with a wetting agent before feeding said portion through adischarge zone.
 65. The method according to claim 64, wherein thewetting agent is a polar wetting agent when the liquid is a polarliquid, and wherein the wetting agent is a non-polar wetting agent whenthe liquid is non-polar.
 66. The method according to claim 62,comprising a further step of lubricating at least a portion of thethread before or after feeding said portion through a discharge zone.67. A device for applying liquid to a single thread as said thread movesrelative to the device along a path of movement, wherein said device isconfigured to apply liquid to said thread by means of at least oneemitter for discharging liquid through a respective discharge nozzletowards the thread in a discharge direction, liquid supplier forsupplying liquid to said at least one emitter, and a thread treatmentdevice for treatment of the thread, wherein the thread treatment deviceis configured to wash the thread, lubricate the thread, or wet thethread.